"Maybe... yes"

"Maybe... yes, but I should have full control when it happens," Hanna says.

You shake your head. "No, the progress of the experiment controls when it happens."

"Then I won't!" she says conclusively.

"Or you could provide a replacement when you are not available," you propose.

"You mean like, other girls?"

You nod.

"No way! I'm not sharing your tongue skills with anyone!" she says in a sudden outburt.

"Really? If you were in my place, what alternative do you think I would have?"

"You would stick to me, 'cause you're my buddy!"

"If we're really buddies, then you should be more accommodating."

"Well, maybe, in **** cases, I could let some of my girlfriends substitute."

"On the other hand, that would introduce additional variability into the experiment. Unless they taste exactly like you!"

She just stares at you blankly, unwilling to decide.

"But if we add one of your girlfriends as a second donor, the experiment could run in parallel for both of you, so if either of you miss, the experiment would not be severly interrupted, as long as both of you never miss it at the same time."

"Why does it have to be scheduled?" She finally asks.

"First, I have to determine if your juice composition changes, and if it does, I also want to know if it follows a trend. Then I'll have to determine causative factors, and ..."

"Ok, ok." She interrupts your explanation. "I get it."

"So, what's your decision?"